Today Twitter was down for some time which led to quite a bit confusion and discussion. What happened? The consensus is that it was a DDoS that caused the downtime of the poular social network. The attack was not solely on Twitter but also directed on Facebook, LiveJournal and YouTube. Back in 2007 WIRED has created a visualization on how a Denial of Service attack works:

While the todays attack wasn’t a traditional DDoS the concept remains mainly the same.